A magneto-resistance element is conventionally used for a magnetic sensor, a memory and the like. The magneto-resistance element is a semiconductor element that uses a magneto-resistance effect, which is a change in resistance according to a magnetic field. A known magneto-resistance element comprises a layer including an alloy having B. Now, a magnetic sensor for measuring an external magnetic field application direction will be described as an example that uses the magneto-resistance element comprising a layer including an alloy having B.
A sensor including a magneto-resistance element such as a TMR (tunnel Magneto-Resistance) element and a GMR (Giant Magneto-Resistance) element is known as a magnetic sensor for measuring an external magnetic field application direction. This magneto-resistance element comprises a pin layer whose magnetized direction is fixed, a free layer whose magnetized direction changes following an external magnetic field, and an intermediate layer disposed between the pin layer and the free layer. This intermediate layer is provided by a nonmagnetic film. In particular, in the TMR element, the intermediate layer is provided by an insulator. When the external magnetic field is applied to the magneto-resistance element, a resistance between the pin layer and the free layer changes according to spin states of the pin layer and the free layer. Specifically, the resistance between the pin layer and the free layer changes according to an angle between a magnetized direction of the free layer and a magnetized direction of the pin layer. For this reason, the sensor can measure the external magnetic field application direction (application angle) by measuring an electric current value flowing in the intermediate layer between the pin layer and the free layer or the like.
For this kind of magnetic sensor, the use of CoFeB (cobalt iron boron) for the pin layer and the free layer, which are magnetic films, has been proposed (e.g., Patent Literature 1). In this magnetic sensor, after the pin layer and the free layer are formed, the pin layer and the free layer in an amorphous state are crystallized by heat-treating. Specifically, in this magnetic sensor, heat-treating after forming the pin layer and the free layer releases B from CoFeB and CoFe (cobalt iron) is used. This is done to increase a magneto-resistance change rate (MR ratio: magneto-resistance ratio) of the magnetic sensor.